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Air-Coupled Piezoelectric Transducers with Active Polypropylene Foam Matching Layers
UMEDIA Research Group, Centre for Physical Technologies, Spanish National Research Council (CSIC), Serrano 144, 28006 Madrid, Spain
Received: 4 March 2013; in revised form: 9 April 2013 / Accepted: 25 April 2013 / Published: 10 May 2013
Abstract: This work presents the design, construction and characterization of air-coupled piezoelectric transducers using 1–3 connectivity piezocomposite disks with a stack of matching layers being the outer one an active quarter wavelength layer made of polypropylene foam ferroelectret film. This kind of material has shown a stable piezoelectric response together with a very low acoustic impedance (<0.1 MRayl). These features make them a suitable candidate for the dual use or function proposed here: impedance matching layer and active material for air-coupled transduction. The transducer centre frequency is determined by the l/4 resonance of the polypropylene foam ferroelectret film (0.35 MHz), then, the rest of the transducer components (piezocomposite disk and passive intermediate matching layers) are all tuned to this frequency. The transducer has been tested in several working modes including pulse-echo and pitch-catch as well as wide and narrow band excitation. The performance of the proposed novel transducer is compared with that of a conventional air-coupled transducers operating in a similar frequency range.
Keywords: air-coupled ultrasound; air-coupled transducers; ferroelectret film; polypropylene piezoelectric foam
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MDPI and ACS Style
Gómez Alvarez-Arenas, T.E. Air-Coupled Piezoelectric Transducers with Active Polypropylene Foam Matching Layers. Sensors 2013, 13, 5996-6013.
Gómez Alvarez-Arenas TE. Air-Coupled Piezoelectric Transducers with Active Polypropylene Foam Matching Layers. Sensors. 2013; 13(5):5996-6013.
Gómez Alvarez-Arenas, Tomás E. 2013. "Air-Coupled Piezoelectric Transducers with Active Polypropylene Foam Matching Layers." Sensors 13, no. 5: 5996-6013.